1. Field of the Invention
The present invention relates to a method of demodulating binary information encoded in an electronic signal.
2. Discussion of Prior Art
Typically it is necessary to transmit binary information over a channel. This channel may be a hard-wired channel or a radio channel. One method of modulating binary information is frequency shift keying (FSK). In frequency shift keying, a one "1" is represented by a first frequency of a carrier signal and a zero "0" is represented by a second frequency of the carrier signal. The transmitted signal has a frequency reflecting the binary information to be transmitted over time.
The demodulation of FSK signals is performed by a balanced frequency discriminator or a matched filter. In a balanced frequency discriminator, the output voltage is a linear function of the input frequency. A balanced frequency discriminator is comprised of a pair of resonant circuits tuned to each of the FSK signaling frequencies. Envelope detectors follow the tuned circuits.
A similar FSK demodulator comprises a pair of filters matched to the signaling waveforms, followed by envelope detectors.
These devices employ analog means of FSK demodulation. Their operation is subject to the inaccuracies and difficulties of maintaining the devices to within the designed tolerances as well as their overall characteristics of having components that are difficult to miniaturize.
Typically, conventional FSK demodulators may not be used in applications which require very low power consumption.
Currently there is a need for an FSK demodulator which is simple, operates well in a low signal-to-noise ratio environment, and has low power requirements.